WINCHESTER — Scott County health officials are encouraging residents to take extra precautions when outside after testing returned more evidence of the West Nile virus in the mosquito population.

The county and several surrounding counties have had tests come back positive for West Nile before, but there was a spike this year, Scott County Health Administrator Steve Shireman said.

“We’ve had positives in Scott, Greene and Calhoun counties for several years,” Shireman said. “West Niles has made itself at home throughout the state of Illinois.”

Each year, counties trap and test a number of mosquito populations; this year, it seemed like there were more positives, he said.

”We did get some better equipment and (it) may be more sensitive, but we did notice an increase in positives (compared to what) we’ve seen historically” Shireman said.

The year’s first case of West Nile virus in an Illinois resident was reported in June, nearly a month earlier that in previous years, according to the Illinois Department of Public Health.

Last year, 63 counties in Illinois reported a West Nile-positive mosquito testing batch, bird and/or human case. There were 90 human cases, including eight deaths, although the IDPH said cases of West Nile in humans are under-reported.

West Nile often is transmitted from a bird to a mosquito and then to a human; the virus often causes fever, nausea, headaches and muscle aches and can last from a few days to weeks.

Anyone can become infected with the virus, but many cases of severe infection happen to older people or those with a weakened immune system, Shireman said.

The increasing number of positive tests makes it increasingly important for people to take precautions to avoid being bitten by a potentially infected mosquito, he said.

“The best thing for anyone to do is to remove any sources where water can collect and any place that can harbor mosquitoes,” Shireman said. “Standing water is a good place for mosquitoes and it can be hard to get rid of some places of standing water.”

Things such as pools, tires, outdoor toys or ponds can collect water for mosquitoes, he said.

It also is important to limit exposure by making sure doors and windows have proper screens to keep out mosquitoes and by wearing long clothes when it is necessary to be outside, he said. Insect repellent also is a necessity.

“Trying to avoid being bit is the best way to avoid getting West Nile,” Shireman said.

Samantha McDaniel-Ogletree can be reached at 217-245-6121, ext. 1233, or on Twitter @JCNews_samantha.